Hysteresis-Free Gate-All-Around Stacked Poly-Si Nanosheet Channel Ferroelectric HfxZr1-xO2 Negative Capacitance FETs With Internal Metal Gate and NH3 Plasma Nitridation

In this study, hysteresis-free double-layer gate-all-around stacked poly-Si nanosheet channel ferroelectric Hf
_x
Zr
_1-x
O
₂
negative capacitance field-effect transistors (DL GAA NS FE-HZO NC-FETs) with an internal metal gate (IMG) and NH
₃
plasma nitridation were experimentally investigated and comprehensively discussed for the first time. The results revealed that NH
₃
plasma nitridation at both the ZrO
₂
/TiN and TiN/HZO interfaces can effectively enhance the HZO ferroelectricity and quality by suppressing the generation of oxygen vacancies (
${V}_{o}{)}$
. Furthermore, the SiON interfacial layer quality can be enhanced by passivating bulk defects within the SiON interfacial layer through NH
₃
plasma nitridation at the ZrO
₂
/TiN interface. When NH
₃
plasma nitridation is performed at both the ZrO
₂
/TiN and TiN/HZO interfaces, the devices exhibit excellent electrical characteristics: 1) an extremely low subthreshold swing (SS) of 45.77 mV/decade; 2) an ultrasteep average SS (ASS) of 61.39 mV/decade; 3) a relatively high ON/OFF current ratio (
${I}_{ \mathrm{\scriptscriptstyle ON}} / {I}_{ \mathrm{\scriptscriptstyle OFF}}{)}$
of
$ > 5\,\,\times \,\,10^{{7}}$
; and 4) a quite high effective breakdown voltage (
${V}_{\text {EBD}}$
) of 6.7 V at
${V}_{D}$
= 0.1 V. Thus, these devices are promising candidates for low-power-consumption monolithic 3-D integrated circuit (IC) applications.